Flow cytometry analysis demonstrated that the γ-secretase inhibitor also reduced the infiltration of MDSCs, TAMs, and Tregs into the spleen, draining lymph nodes and the TME as well as decreasing the expression of ICs (e.g., PD-1, CTLA-4, TIM-3, and LAG-3) in T cells in the circulation and tumor TME [19]. Here, PDCD1 is linked to neoplasm.